Various types of systems have been incorporated into athletic shoes in an attempt to improve upon the energy return characteristics and comfort of the shoe. For example, a cushioning midsole material is commonly incorporated into portions of the sole of an athletic shoe to lessen the impact when the shoe strikes the ground. Other types of athletic shoes have fluid bladders in portions of the sole to cushion the sole. The fluid may be simply air, and sometimes the pressure of the fluid in the bladder may be adjusted by the wearer to alter the cushioning and/or rebounding properties of the shoe.
Another type of energy return system for athletic shoes employs the use of netting or a mesh arrangement in selected portions of the sole construction. For example, U.S. Pat. No. 5,070,629, issued Dec. 10, 1991, discloses an energy return system that includes a rigid frame with a set of monofilaments or fibers secured under tension across the frame. The monofilaments or fibers form a spring-like grid system that stores energy during the compression portions of the gait cycle and releases energy during the push-off phase of the gait cycle. U.S. Pat. No. 5,402,588, issued Apr. 4, 1995, U.S. Pat. No. 5,561,920, issued Oct. 8, 1996, U.S. Pat. No. 5,595,002, issued Jan. 21, 1997, U.S. Pat. No. 5,852,886, issued Dec. 29, 1998, U.S. Pat. No. 5,974,695, issued Nov. 2, 1999, and U.S. patent application Ser. No. 10/723,977, filed Nov. 26, 2003, disclose various improvements to this spring-like energy return system, all of which are herein incorporated by reference in their entirety.
It is an object of the present invention to provide an improved energy return and cushioning system for a shoe.